The present invention is directed to a device for delivery of medicament, and in particular to a compact jet injector and loading system used with standard medicament cartridges.
A wide variety of needle free injectors are known in the art. Examples of such injectors include those described in U.S. Pat. No. 5,599,302 issued to Lilley et al., U.S. Pat. No. 5,062,830 to Dunlap, and U.S. Pat. No. 4,790,824 to Morrow et al. In general, these and similar injectors administer medication as a fine, high velocity jet delivered under sufficient pressure to enable the jet to pass through the skin.
Although these injectors are quite successful from a technical point-of-view in achieving the desired delivery of medicament, most commercially available needle free injectors have practical limitations. For example, most needle free injectors are bulky in size. In addition to the undesirable size, some needle free injectors require a complex sequence of coupling and uncoupling the injector to a vial containing the medicament. Thus, there is a perception by the user that the injector is difficult to use. Finally, some needle free injectors cannot be used with standard medicament cartridges, i.e. a cylindrical chamber, typically made of glass, having a first end with a seal penetrable by a needle to draw medicament out of the cartridge and a second end with a movable stopper.
Thus, there exists a need for an improved medical injector and loading system that is compact, usable with standard medicament cartridges, and perceived as easy to operate.
The present invention is directed to a cap for a medicament cartridge. The cartridge has a chamber containing medicament, a first end of the chamber having a seal, and a second end of the chamber having a stopper movable towards the seal as medicament is drawn out of the chamber. The cap according to the present invention comprises an interior portion for receiving the second end of the chamber and a post for causing movement of the stopper toward the seal when the cap engages the medicament cartridge to thereby eliminate adhesion between the chamber and the stopper.
The adhesion-eliminating cap can be used in combination with an adapter for transfer of medicament out of the cartridge. The action of the cap in conjunction with the adapter is to allow the purging of gas or air from the cartridge and thus assist in better dosage accuracy and injection quality. The adapter has a first side that mates with the first end of the chamber and has a needle for penetrating the seal upon insertion of the cartridge assembly in the adapter, a second side, and a wall between the first and second sides. The wall has an opening in fluid communication with the needle to create a pathway for medicament as medicament is drawn out of the chamber. Preferably, the first side of the adapter has a plurality of resilient tabs that flex outward upon insertion of the medicament cartridge into the adapter and flex inward after the seal is substantially flush with the wall for locking the medicament cartridge into the adapter.
In one embodiment, the cap and adapter are coupled with a housing. The housing has a first end connectable with the cap and a second end connectable with the adapter. The housing can include a window for visualization of at least a portion of the medicament cartridge.
The cap according to the present invention can be used with a wide variety of injection devices, including a needle free injector. Preferably, the needle free injector comprises a needle free syringe assembly and a power pack assembly. The needle free syringe assembly includes a nozzle member defining a fluid chamber and having a proximal end that mates with the second side of the adapter. The needle free syringe assembly also includes a plunger movable in the fluid chamber. The power pack assembly includes a housing having a proximal end connectable with the distal end of the nozzle member, a trigger assembly, and an energy source operatively associated with the trigger assembly. Movement of the trigger assembly activates the energy source to move the plunger in a first direction to expel medicament from the fluid chamber when the adapter is not connected to the needle free syringe assembly and movement of the plunger in a second direction draws medicament out of the cartridge chamber and into the fluid chamber when the adapter is connected to the needle free syringe assembly.
In one embodiment, the first end of the cartridge assembly housing has a female thread and the cap has a collar insertable into the first end of the cartridge housing. The collar is provided with a male thread that mates with the female thread for connection of the housing with the cap.
The present invention can be used with lyophilized medicament. Specifically, the medicament chamber has a first chamber containing a lyophilized medicament, a second chamber containing a reconstituting fluid, a dividing member separating the first and second chambers, and a bypass channel for providing fluid communication between the first and second chambers upon movement of the dividing member. Fluid pressure generated by movement of the stopper causes movement of the dividing member. The attached adapter assembly allows the venting of the gas or air from the first chamber thereby facilitating dividing member movement and fluid flow. This also allows minimizing the air or gas present in the reconstituted fluid prior to injection.
The present invention is also directed to a medical injector assembly comprising a cartridge assembly for holding a medicament cartridge and a syringe assembly. The medicament cartridge has a chamber containing medicament, a first end of the chamber with a seal, and a second end of the chamber with a stopper movable towards the seal as medicament is drawn out of the chamber. The cartridge assembly comprises a cap with an interior for receiving the second end of the chamber and an end having a post causing movement of the stopper toward the seal as the medicament cartridge is inserted in the cap to thereby eliminate adhesion between the chamber and the stopper. The syringe assembly comprises a fluid chamber, a needle, and a plunger. The plunger is movable in the fluid chamber so that movement in the first direction expels medicament from the fluid chamber. Movement of the plunger in the second direction draws medicament out of the cartridge chamber into the fluid chamber when the syringe assembly is in fluid communication with the medicament cartridge. In one embodiment describing such fluid communication, the needle on the syringe assembly penetrates the seal on the first end of cartridge chamber. Another embodiment anticipates a receiving member for the syringe needle in the adapter. The seal penetrating needle in this embodiment is integral to a first side of the adapter (the side that mates with the first end of the cartridge chamber). The second side of the adapter consists of a receiving member for the syringe and syringe needle designed as to allow fluid communication with the first side of the adapter.